* Initial GLTFLoader updates so it will also obtain async resources over the network

* First take at adding shader support to new GLTFLoader

* First working custom shaders version of GLTFLoader.js

* Fully working custom GLTF shaders + general library fix-ups

* Add skins, animations, lights, extensions and continue to refactor the library

* Refactor new GLTFLoader (seperate glTF parsing and internal library building)

* Fix GLSL shader update binding to point at the correct nodes + more general refactoring

* Make _each thenable and refactor dependencies graph + other minor fixes

* Improves spec compliance: primitive.mode is optional

* Update GLTFLoader v2 with feedback on PR: https://github.com/mrdoob/three.js/pull/9786

- Replace .set(...) with .fromArray(...) where possible for THREE.js Math objects (thanks @mrdoob)
- Include fix for https://github.com/mrdoob/three.js/issues/8381 (thanks @cx20)
- Move THREE.GLTFShaders to THREE.GLTFLoader.Shaders
- Move THREE.GLTFAnimator to THREE.GLTFLoader.Animations
- Rename .setBaseUrl(...) to .setPath(...)
- Update demo page 'examples/webgl_loader_gltf_new.html' with renamed APIs

* Replace 'examples/webgl_loader_gltf.html' with new version of GLTFLoader

* Update documentation at /docs/?q=gltf#Reference/Loaders/GLTFLoader to reference new GLTFLoader

* Move /examples/js/loaders/gltf/* to /examples/js/loaders/deprecated/gltf/*

* Actually add a fix for https://github.com/mrdoob/three.js/issues/8381

* Re-fix https://github.com/mrdoob/three.js/issues/8381 in a more logical way

* Update material parameter checking and validation.

* Fix issue whereby the spec says doubleSided and transparent should be in the 'values' section but every use of these params I've seen in the wild has been outside this section

* Ambient is not a valid properties for THREE.js materials

* THREE textures have flipY set to true by default. By setting to false we can remove double flip from GLTFLoader

* Fix issue where Firefox Promise then callback can not correctly keep track of its key

* Remove debugging from examples/loaders/deprecated/gltf/glTFLoader.js

* Refactor waitForDependencies in to _withDependencies. Remove need for global library.* tracking. Other general refactoring